1. Field of Invention.
This invention relates to devices for reclaiming heat, more particularly to devices for reclaiming heat from stove pipes, furnace flues, and the like.
2. Description of the Prior Art.
All devices which generate heat lose a proportion of that heat during generation and any subsequent transportation of that heat. A primary example exists with respect to a wood burning stove. The combustion of the fuel serves to create by-products of heat. Some of this heat is dissipated in the body of the stove itself, some is dissipated in heating the air inside and surrounding the stove, and other heat is dissipated through the exhaust by-products of combustion and into the exhaust pipe or stove pipe which carries these exhaust by-products. Therefore, the heat contained in the exhaust stage presents an attractive source for heat reclamation, as it would more or less be wasted by exhausting it.
Various attempts to reclaim this heat have been made in the past, employing various designs.
A majority of the prior heat reclaimers utilize designs which completely surround a stove pipe or furnace flue. An air chamber is then primarily heated by the radiant heat of the stove pipe and then exited for use by a blower or fan. This type of design does avoid using or processing the exhaust by-products, which would make the device much more complicated and potentially unsafe because of harmful exhaust fumes, but it relies solely on the radiant heating of the air in its chamber for heat reclamation.
Improvements upon this design worked to modify the stove pipe itself to present a larger stove pipe area to the air chamber to allow more heat to be transferred to the air. Typical of this design is the Feldman U.S. Pat. No. 4,117,883, which utilized a plurality of pipes connected in parallel with the stove pipe and which in turn were surrounded by the air chamber. Again, the heat transfer occurs solely on the basis of conduction of the pipes to the air. Though efficiency may be increased by presenting a larger surface area of stove pipe to the air, the increased size of the air chamber decreases the efficiency by which the air may be heated.
Alternatively, devices were designed to be inserted between sections of a stove pipe or the like. This required greater complexity and flexibility in design, though the principles remain basically the same. Generally, these designs attempt to extract heat from the exhaust of a heat source, by having the exhaust directly contact the device and then conducting the extracted heat to an air chamber. Some designs also use conduction from the pipe through solid material to transport the heat to the air chamber more efficiently. However, all these types of prior devices completely surround the exhaust channel thereby contributing to the problem of creosote build-up on the inside of the exhaust channel. Additionally, the air chambers of these devices are usually large in volume, thereby reducing the potential efficiency of the heat reclaimers.
Creosote build-up is a significant problem in that its build-up on the inside of a stove pipe, furnace flue or exhaust channel not only reduces the efficiency of the heat source, whether a stove, furnace, or the like, but greatly increases the danger of "chimney fire" or back up of noxious or toxic fumes. Some heat reclaimers have attempted to solve this problem by relying on metal-to-metal heat conduction in order to heat the air chamber and then subsequently exhaust the heated air by a fan or blower. Was, U.S. Pat. No. 4,103,826 is an example of such a device. However, it is inefficient because the contact area between the stove pipe and the device is very small; a tubular surface against a tubular surface. Also, the large air chamber of Was causes any conducted heat to dissipate quickly, thereby further rendering the device rather inefficient.
It is therefore an object of this invention to provide a heat reclaimer which is thermo-dynamically efficient.
Another object of this invention is to provide a heat reclaimer which provides a large conductive contact surface with the heat source, but does not unduly enhance the potential for creosote build-up.
Another object of this invention is to provide a heat reclaimer which presents a large heat dispersing area to the air chamber for efficient reclamation of heat.
A further object of this invention is to provide a heat reclaimer which has a high ratio of heat dispersing area to air chamber volume, so that heat is not quickly dispersed within the air chamber before it can be exhausted for use.
Another object of this invention is to provide a heat reclaimer which may be easily installed in existing facilities and which requires no modification to the existing structures.
Another object of this invention is to provide a heat reclaimer which has a highly thermal conductive contacting surface with the heat source.
A further object of this invention is to provide a heat reclaimer which may be thermostatically controlled in its operation.
Additional objects, features and advantages of the invention will become apparent with reference to the accompanying specification and drawings.